The postal services of many countries around the world permit and/or require the printing of postal indicia that include two dimensional barcodes. Such indicia are commonly referred to as Digital Postage Marks (DPM). DPMs typically may include a number of information items in human readable and/or machine readable form, such as, for example, and without limitation, the paid postage amount, the date and time the indicium is generated, the identification number of the postage meter used to generate the indicium, the ascending register value, a postal service symbol, the class of service desired for the mail piece, the addressee ZIP code and/or address, and the sender's name and/or address. For example, the United States Postal Service has implemented a program known as the Information Based Indicia Program (IBIP) which permits the user to generate a postal indicium for sending a mailpiece (e.g., a letter, a package, etc . . . ) that includes a human readable portion and a machine-readable portion in the form of a two dimensional barcode, such as, without limitation, a Data Matrix symbol.
As is known, a two dimensional barcode, such as a Data Matrix symbol, typically consists of a number of data regions having nominally square modules arranged in an array, wherein each module generally represents one bit of data. For a black on white Data Matrix symbol, for instance, a darkened (i.e., filled) module represents a binary “one” and a light (e.g., empty) module represents a binary “zero.”
Despite the numerous advantages that are provided by the use of two dimensional barcodes in postal indicia, many individuals find such two dimensional barcode to be aesthetically unpleasing. Accordingly, it would be advantageous to be able to conceal a two dimensional barcode appearing in a postal indicium from individuals under normal conditions while allowing a postal service to view the two dimensional barcode when desired.